No other senior royals appeared at the event which saw Harry give a reading and actor Damian Lewis recite a poem.
A statement from Harry’s spokesman read: “The duke of course is understanding of his father’s diary of commitments and various other priorities and hopes to see him soon.”
Once he leaves the UK, Prince Harry will visit Nigeria with Meghan Markle after they were invited by the country’s chief of defence staff, who met Prince Harry during the Invictus Games held last year in Germany.
It is understood that Harry will depart Britain in the coming hours, as he is due to meet with Meghan and their team from Archewell in the latter part of this week.
It comes after the King began a return to public engagements, having had to avoid crowds and public meetings after it was revealed that he had an unspecified form of cancer.
His treatment is continuing but the King’s medical advisers have allowed him to start a gradual return to public engagements.
